Steam-engine valve gear



March 23 1926. 1,577,914

J. A. LE cAlN STEAM ENGINE VALVE GEAR Filed Nov. 8. 1921 3 Sheets-Sheet l Jag'. l' Z 4o i JJ 321| J3 35 I I 26 34 E. 34 24 i 2/ 3" 25 ,30' -38" Z0 n i 27 29. 1 27 as -za' L *d5/f 2 .9 1.51"". I 29 33' y M1 cnf/149415' March 23 1926. l.

J. A. LE CAIN STEAM ENGINE VALVE GEAR Filed Nov. s, 1921 3 Sheets-Sheet .2

III/ff fn 5 vente@ March 234 1926.

J. A. LE GAIN STEAM ENGINE VALVE GEAR Filed'Nov. 8, 1921 .3 sheets-sheet s (y anvmtoz do gtie/'maja valve or valves.

Patented Mar. 23, 1926.

UNITED stares JOFL'N' 13E UADT, OFM'ALDEN, MASSACHUSETTS STEAMLENGINE VALVE GEAR.

Appiicatmn ma November s, um.. amar Nm 51eme.

To all whom tf-may comer/n.1

Beit known1 that I, .loam la. LE: (3am, a citizenot the United` States, residing at Malden, county ort Middlesex, Sta-te et tiassacl-iusetts,y have invented certain new and uset-ul Improvements inv Steamf-Engine Valvel Gnears, 'lu-l-ly described represented in the following.` speei-icationy and. the: conapanyiafig drawings-tormirngfa part, ot the saine.. v Y

lihisinvention rela-testo valve gear :iorf fluid pressure engines,.and= more p axticularly to internal valve` gear for` ste-ain` pumping enginesy in which aY pressure actuated nia-in. valve governing the distribution ot steam toopposite sides of working piston` is` controll/3d by a pressure acti-iatedi auxiliary In constructions otV this type dfiiiculty arises.V in starting when the main.l valvel has. accidentally stopped' cen.- ter position, thereby preventing the passage. o't steam. to'- one en -d or the other et. the nlain cylinder.. n c Y The especial object of. this invention is. to.y provide an. improved,` constructiono ttliisv type so. arranged. that. the inai'n` valve. will. be ino,vedf tro1n its center position,V autor maticaily upon turning on. the. steam.47

For a tuti understanding'l ofthe inventioln. a detailed description ot a construction ein.-A bodying the same. itspfreerred torno.- Willi now be given, in connection with the accompanying, dra-Wings, forming a part of. this specification, and the features forming-the invention then.A particularllypointed out in Y the claims in tlie drawings,.-

Fig. l a. sectional view of the vallvegear vtransverse to the steam cylinder; 2 is a section onithefline 2-2of l;

3' is a diagrammatic layout of the Fig. steain and auxiliary cylinders vatve gear valve gear of the above type7 which isV erably that of my Patent No. 153905625- dated-.September 13 w21-,fand then: descritte in detaill the inaproveinentsVv appli-ed thereto:

andv toriningimy invention.

'.Ihe-

piston'L 10 is reeiprocated Within; the, cylinder Il. leyv steam; directed to..r one enrl or other et the cylinderlli thronghports. andf passages L5: and y1i6- which serve-A alternately as induction'. and.y exhaust ports and. passages according to the position oi? the main slide value2()E Whichreciprocates upon; a valve; seat 9. provided withthey usuat exhaust port and passage 14e Asteam chest 13- encloses the valve-seat 9 andreceives steam'. through; a supp-ly passagel.- connectingwith. the interior thereof andi the exhaustv port and passage, le; connects.4 Witlr ak port 19 tor; the discharge 0.1"? thev exhaust steam. The main-A slide valve. is;l neciprecatedi by' a plunger 2l, the opposite end-s of which reciprocate in cylinders-.22 and 23` termed at opposite. of the steam chest;`

Equal pressures.. are normally vexerted against the opposite endsV of' the plunge-r: 2t so1 that it is maintained. ini position to Whichfi't is inovech` The reciproeation ot the plunger 2l is due tothe unbalancede pressuresat opposite endsv tliereoalv causedhy alternately shutting of` the steam supply tor one ortlie other of" they cylinders 22', 23, and simultaneously opening` that saine cylinder to. exhaust..

This operation is accomplished under the: control` otf tWo auxiliary vvalves 2a and 25 which reciprocate. auxiliary valve casings 28-281 secured to. opposite ends of the` steain'chest 13,. Since these. auxiliary ,valves are. identical in construction and operation it will'onl'y be necessary to, descrileftlie valve 25.'v The. auxiliary val've 2`''isy provided at.

its top with an. enlarged head 26 and near its loWer end?. With a` reduced. portionV 272,' The auxiliary cylinder 23 i-'s connected to.V the interior ofthe auxiliary vaivecasingg 28u by an inlet passageA 29 and` an exhaust passage 30', and, the. interior of the casing 2S' is connected by Va passage 31' with. the main exhaust passage, le and` provided-.with a supply passage 32. connecting Wi'tlaftlie interior of the. steam cliest 13'. The several" ports and passages j'ustV described(y are so l'ocatedl` relatively to. each other andthe reduced portion 27;' that when the vave 25 is in its lowerinost or normal position steani. is ad'- init-ted to the adjfacent cylinder 23f through the passage 32, the annular space 33 around the reduced portion of the valve 25 and passage 29 while communication is obstructed between the exhaust passage 30 and the passage 31. When the valve 25 is raised to operative position the passages 29 and 32 are disconnected, thus shutting ott' the supply of steam to the cylinder 23 while communication is established between the exhaust passages 30 and 31, thus exhausting the steam from cylinder 23.

Y The auxiliary valve 25 is raised into operative position by the admission ot steam from the main cylinder 11 to an annular space 34 formed beneath the head 26 of the valve through a passage 35 which terminates in a flaring port 36 in one side ot the slide valve seat 9 adjacent to the upper end of a passage 37 Which opens at 37 into the main cylinder l11 near the left end thereof, as shown in Figs. 2 and 7. A groove 38 in the under face of the main slide valve 2O connects the valve seat terminals of the passages 35 and 37 when the main valve is in its extreme position toward the lett (Fig. 3) so that live steam trom the right side ot the piston 10 may pass to the space 34 and quickly cause the operative stroke ot the auxiliary valve 25 when the main piston in its stroke to the lett opens the passage 37 to `the live steam driving the main piston 10.

The operative stroke of the auxiliary valve '25,as previously stated, shuts off the tlow of liv-esteam to the auxiliary cylinder 23 and simultaneously opens said cylinder to exhaust thus unbalancing the pressures in v,the auxiliary cylinders 22 and 23, whereby the plunger 21 moves to the right carrying with it the main valve 2O for the delivery of steam to the lett end or" the main cylinder for the reversal of the main piston 1G.

Movement of the main valve 20 to the right connects the flaring port 36, valve seat terminal ot the passage 35, through groove. 38,.with a lateral extension 39 ot the port and passage 16 which, being now connected to the exhaust passage 14, allows the steam to exhaust from the space 34 beneath the head 26 ot the auxiliary valve 25. Simultaneously live steam is passed from port and passage 15 through passage 4() and ports 41 and 42 to the top and the bottom o1p4 the auxiliary valve 25 whereby the' valve is positively and gently forced down to its normal position by reason of the difference of area between the top and bottom surfaces of the valve.

The auxiliary valve 24 is the same in structure as the auxiliary valve 25 and is connected with the main cylinder and the exhaust passage by means of a series of pas sages identical in formation and arrange ment with the passages connected with the auxiliary valve' 25 and are designated by crepondiim' reference numerals primed,

with the sole exception of the passage 37 and its opening 37 which are marked respectively 37a and 37b. l/Vherefore, the movement of the main valve to the right connects the space 34 under the head 26 of the valve 24 with the opposite end ot the cylinder through passages 35', 37a and groove 38 on the opposite side of the valve seat 9, so that when the piston 10 in its movement to the right uncovers the opening 37b ot the passage 37a, the auxiliary valve 24 undergoes the same operation as above described in connection with the auxiliary valve 25 to produce an opposite movement of the plunger 21 and the main valve 20 to secure a reversal ot' the main piston 10.

Referring now to the features added in accordance with the present invention, and by which the automatic throw of the valve, it stopped on dead center, is secured', in the preferred construction shown, I provide the main valve 2O with a steam lap ai and a negative exhaust lap y as shown in Fig. l, so that, when the main valve 2O is in its dead center position, steam will not pass to either ot the passages 15 and 16, and these vpassages will be under the same pressure,

that is, exhaust pressure, as they will be connected to each other and the exhaust passage 14 by the negative exhaust lap y. Since passages 40, 40 connect respectively with the passages 15, 16, the top and bottom ot each of the auxiliary valves 24 and 25 will be under exhaust pressure. ln order to assure movement of one or the other ot the auxiliary valves 25 and 25 on turning on the and 2a adapted to connect with the passages 1 and lEL respectively when the main valve 2O is in its dead center position.

The operation of this device is as follows: When the steam is turned on it passes through the passages 1 and 1a, the slots 2 and 2a, grooves 38, 38 and passages 35, 35 to the spaces 34, 34 beneath the heads 26, 26 ot the auxiliary valves 25 and 24, Whereby, due to the difference ot pressures in the ports and passages, and the difference in the force required to start the auxiliary valves 24 and 25 from their normal positions, one valve will move to operative position ahead of the other and in so doing will connectl that end ot' the plunger 21 to the exhaust, thus causing a movement ot the main valve 2O from its dead center position and delivering steam to one end ot the main cylinder 11, whereby the valve gear will resume its normal operation as set forth previously.

lt will be understood that the invention gear shown, nor to the detail construction llO or arrangement of the parts, as the invention is applicable to othervalve gears and many modifications may be made within the invention is defined by the claims.

That is claimed is:

l. A fluid pressure engine comprising a main cylinder and steam chest, a fluid actuated main valve controlling the distribution of steam to and from the main cylinder, a liuid actuated auxiliary valve controlling the movement of the main valve, and means operating When the main valve is stopped in dead center position to move the auxiliary valve by applying unbalanced pressures thereon whereby the auxiliary valve vvill be moved When steam is admitted to the steam chest. v

2. A fluid pressure engine comprising a main cylinder and steam chest, a fluid actuated main valve controlling the distribution of steam to and from the main cylinder, a fluid actuated auxiliary valve controlling the movement of the main valve, and means controlled by the main valve operating when the main valve is stopped in dead center position to move the auxiliary valve by applying unbalanced pressures thereon.

3. A fluid pressure engine comprising` a main cylinder and steam chest, a fluid actuated main valve and` its seat, a fluid actuated auxiliary valve controlling the movement of the main valve, a passage connecting the steam chest and the main valve sea-t, a passage connecting one side of the auxiliary valve Wih said seat, a groove in the main valve adapted to connect said passages when the main valve is in dead center position, and ports connecting the other side of the auxiliary valve With the exhaust in said position of the main valve.

4. A fluid pressure engine comprising a main cylinder and steam chest, a fluid actuated main valve controlling the distribution of' steam to and from the main cylinder,

a fiuid actuated auxiliary valve ,controlling the movement of the main valve, said main valve being arranged to provide a steam lap and a negative exhaust lap in the central sosition of the valve, and ports controlled by the main valve adapted to connect one side of the auxiliary valve Vith the steam chest and the other side with the exhaust when the main valve is in dead center position. Y

5. A fluid pressure engine comprising a main cylinder and steam chest, a fluid actuated main valve and its seat, a fluid actuated auxiliary valve controlling the movement of the main valve, said main valve being arranged to provide Ya steam lap and a negative exhaust lap in the central position` of the valve, a passage connecting the steam chest and the main valve seat', a passage connecting one side of' the auxiliary -valve with said seat, agroove in the main valve adapted to connect said passages when the main valve is in dead center position, and ports connecting the other side of the auxiliary valve With the exhaust in said position of the main valve.

6. A fluid pressure engine comprising a main cylinder and steam chest, a main slider lmain valve plunger, two separate auxiliary valves, means controlled by said auxiliary valves for admitting live steam to normally maintain live steam pressure upon opposite ends of the plunger, means controlled by 'each of the auxiliary valves for momentarily relieving the steam pressure upon one end of the plunger, and ports and passages for applying unbalanced pressures to move one of the auxiliary valves when steam is turned on with the main valve in dead center position.

8. A fluid pressure engine comprising a main cylinder and steam chest, a main slide valve and its seat, a normally balanced plunger for moving the main valve, pressure actuated auxiliary valves controlling the movement of said plunger, means for applying unbalanced pressure tending to move the auxiliary valves When the main valve is in dead centre position con'iprisinp passages 35, 35 connecting one side of each ofthe auxiliary valves With the opposite sides of the main valve seat, passages l and lfL connecting these same opposite Ysides of the main valve seat with the steam chest, grooves 38, 38 in each of the corresponding opposite edges of the main valve, slots 2 and 2 extending from the grooves 38, 38 and adapted to register respectively with the passages l and la when the main valve is in dead center position, and ports and passages arranged to connect the other side of each of the auxiliary valves With the exhaust in said position of the main valve.

in testimony whereof, I have hereunto set my hand. f

JOHN A. LE GAIN. 

